During drilling of wellbores it is common practice to form a filter-cake layer at the borehole wall to limit outflow of drilling fluid into the earth formation surrounding die wellbore. Included solid particles in the drilling fluid which block the pores of the earth formation at the borehole wall, conventionally forms the filter-cake layer. A polymer is furthermore included in the drilling fluid for the purpose of binding the particles to each other. The filter-cake is created by limited leak-off of drilling fluid into the earth formation. When production of hydrocarbon fluid is to be started, it is necessary either to remove or bypass the filter-cake layer. It has been tried to remove the filter-cake layer by producing hydrocarbon fluid from the earth formation into the wellbore (“back flowing”), or by dissolving the layer using acid. Back flowing is normally inefficient because the flow rate is generally too low to remove the filter-cake layer, especially for long horizontal wellbore sections. Acidizing also is generally inefficient because once the acid has dissolved a portion of the filter-cake layer, the remaining acid tends to enter the formation at the location of the removed portion.